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Ryegrass, Perennial

[Lolium perenne L.] DESCRIPTION

Perennial ryegrass is a bunch-type grass that is used for winter overseeding on sites where high quality and winter color are needed. The texture, color, and density of perennial ryegrass are very similar to those of Kentucky bluegrass. Perennial ryegrass is often utilized for winter overseeding on golf course fairways and teeboxes, athletic fields, and high profile home lawns. Perennial ryegrass is often confused with tall fescue and/or Kentucky bluegrass. However, Kentucky bluegrass has a boat-shaped leaf tip and distinctive light-colored lines on both sides of the midrib. Tall fescue has rough leaf blade margins whereas perennial ryegrass has smooth ones. Also, tall fescue has rolled vernation in the leaf bud and perennial ryegrass has folded vernation.


Seedhead / Flower Vernation Type Ligule Type Growth Season / Life Cycle Auricle Type Leaf Blade Tip Shape Leaf Blade Width Stolon Presence Rhizome Presence Collar Type Sheath Margin Sheath Type


a spike, with flattened spikelets along each stem leaves folded in the bud membranous; collar-like to blunt, may be toothed near top, 0.02 - 0.06 inches (0.5 - 1.5 mm) long cool season turf or perennial weed rudimentary sharp-pointed; bright green, sharply creased, deeply ridged upper surface, lower surface smooth and glossy, edges slightly rough 0.08 - 0.2 inches (2 - 5 mm) wide absent absent divided by midrib, not hairy, distinct sheath is usually flattened, reddish at base

perennial ryegrass

perennial ryegrass ligule

Note: Still not sure this is the right weed? The Turf & Weed Identification Decision Aid may help. Check the TurfFiles glossary for definitions of unfamiliar terms.


Perennial ryegrass is often overseeded to provide winter color in warm climates where turf is utilized in winter months. When warm weather prevails in late spring or early summer, this species usually will not survive. However, in the transition zone, especially during cool summers, wet summers, or both, perennial ryegrass can survive the summer and often becomes clumpy. This very attractive turf species becomes a difficult-to-control weed in these conditions. Control strategies should concentrate on controlling perennial ryegrass before it becomes clumpy.


Sulfonylurea herbicides including Manor, Monument, Revolver, and TranXit offer control during spring transition. Additionally, increased rates offer control once ryegrass becomes clumpy. All sulfonylurea herbicides exhibit reduced efficacy when applied under cool conditions or when cool conditions are present after application, and this problem is exacerbated with Revolver. An unacceptable level of control may be observed under unfavorable weather conditions. Preemergence herbicides: Range of Trial Efficacy Values, % 70 - 99

Herbicide rimsulfuron** Postemergence herbicides:

Tolerant (1) Turfs be

Average Efficacy (2) Rating G

Number of Trials 2

Products TranXit GTA


Herbicide foramsulfuron atrazine* trifloxysulfuron-sodium rimsulfuron** glyphosate

Tolerant (1) Turfs be, z be, c, sa, z be, z be

Average Efficacy (2) Rating E E G G G

Range of Trial Efficacy Values, % 64 - 100 76 - 98 68 - 100 51 - 100 46 - 98

Number of Trials 25 3 27 26 6

chlorsulfuron * **

bc, be, bk


80 - 85


Products Revolver AAtrex 4L Monument TranXit GTA Glyphosate Original, Roundup, Touchdown Pro** Corsair


For use only by or under the supervision of a certified applicator, or by commercial nursery, turf, and landscape personnel. Not for application to residential lawns.

Footnotes: (1) Turfgrass Codes: ba bahiagrass bc bentgrass, creeping be bermudagrass bk bluegrass, Kentucky


c f r sa z blank

centipedegrass fescue, tall ryegrass, perennial St. Augustinegrass zoysiagrass No turfgrass in the database is completely tolerant. Check label to see if chemical can be used at a reduced rate or during the dormant season on your turfgrass.


Efficacy Ratings: E excellent control (90 to 100%) G good control (80 to 90%) F fair control (70 to 80%) Efficacy ratings are based on herbicide trials performed by weed scientists at North Carolina State University between 1997 and 2007. The number of trials included in the efficacy ratings is displayed in the next-to-last column. The higher this number, the more confidence can be placed in the efficacy values. Trials may have involved sequential applications of one or more chemical. Details of individual trials (herbicide rates, dates of application, environmental conditions at time of application, etc) can be viewed on the TurfFiles web site, through the Turf Weed Management Decision Aid. Efficacy ratings for chemicals lacking trial data are from "Pest Management Strategic Plan for Turfgrass in the Southern United States," a summary of a workshop for turf experts from multiple universities held in Griffin, GA in October, 2004. The workshop was sponsored by the Southern Region Integrated Pest Management Center.


Recommendations of specific chemicals are based upon information on the manufacturer's label and performance in a limited number of trials. Because environmental conditions and methods of application may vary widely, performance of the chemical will not always conform to the safety and pest control standards indicated by experimental data. The order in which brand names are given is not an indication of a recommendation or criticism. Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services does not imply endorsement by North Carolina State University or discrimination against similar products or services not mentioned. Other brand names may be labeled for use on turfgrasses. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your county's Cooperative Extension agent.

Links contained in this document: Glossary: Pest Management Strategic Plan: Turf & Weed Identification Decision Aid: Turf Weed Management Decision Aid:

© North Carolina State University. This information sheet was prepared by Fred Yelverton, Bridget R. Lassiter, Gail G. Wilkerson, Leon Warren, Travis Gannon, Jenifer J. Reynolds, and Gregory S. Buol. Department of Crop Science, College of Agriculture & Life Sciences, North Carolina State University. Prepared April 2, 2008. Available on-line at This publication was made possible through a grant provided by the Center for Turfgrass Environmental Research & Education (CENTERE) whose purpose is to support worthwhile projects that will benefit both the private sector and the public, and protect the environment.



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